Automatic telephone system



April 6 1926. 1,579,838

W. T. POWELL AUTOMATI C TELEPHONE S YSTEM ATTORNEY April 6,' 192s.1,579,838

W T. PQWELI.

AUTOMATIC TELEPHQNE SYSTEM Filedl March 6. 1923 4 Sheets-Sheet 2 m gvgpGENERATOR FIG, 'Z

C0 NN ECTOR INVENTOR W I N FRED T. POWELL ATTORNEY April 6 1926.1,579,838

W.T. POWELL.

AUTOMATIC TELEPHNE SYSTEM Filed March e, 192: 4 sheets-sheet :s`

ATTORNEY April 6 1926.

' w. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed March 6. 1923 4Sheets-Sheet 4 Mm .Pm-OMM n.; 2.3

...una DZDOK DZ( JUK m O OF Grimm ofzow :un: E'

lNvENToR WINFRED T. POWELL ATTORNEY Patented Apr. 6, 1926.

unirsi) stares rarest ois-rice. g

WINFRED T. POWELL, OF ROCHESTER, lilEl` YORK, ASSIGNRTO THE STROMBERG-CARLSON TELEPHONE MANUFACTURNG COMPANY, OF ROCHESTER, NEW' YORK, A

CORPORATION OF- NEW' YORK.

AUTOMATIC TELEPHONE SYSTM. *i

iippiicmion ined March e, 192s. semi no. seance.

To @ZZ iii/wm it may vcon-cera:

Be it known that I, linmean T. Powiim., a citizen ot the United States,residing at Rochester, in the county oi Monroe and State oit New ,Yorinhave invented certain new and useful improvements in Automatic TelephoneSystems, oi which the following isa full, clear, concise, and exactdescription. i

This invention relates to telephone systeiiis and more particularly totelephone systems employing automatic switches in completing 4someportion of a telephone connectionbetween calling and called subscribers.

The present invention has for its purpose the provision o'lI iiieanswhereby a thei'niionic device directly controls the operation ot one ormoreprogressively movable automatic switches. Other features of theinvention reside inthe novel circuit arrangement 'for accomplishing thispurpose.

'lhe drawings with Figs. `1 and 2 arranged in the order nameddiagraniiiiatically represent a portion ot` a telephone systemVeinploying the present invention. The portion et Fig. l at the lett ofthe dotted line representsv a calling subscribers telephone line and anon-numerical switch or a line switch for f extending this telephoneline. rit the right of the dotted line in Fig. 1 there arerepresentedtho operating circuits ot` a numerical or selector switch..ln Fig. 2 there are shown the operating circuits of a connector switch,while at the upper right hand corner of this ligure there is representeda called telephone line. Figs. 3 and 4"represent a modified form ot theinvention in which tlierinionically controlled circuits govern thevariable setting of a register sender.

The non-nuiiierical switch or line switch and registers referred `to maybe substantially similar in structure to that disclosed in the patent toClement 1,107,153, granted August 11, 1914, while the oilieratingcircuits of the line switch of F ig. l may be substantially similar tothose shown in F ig. 49 on page 52 of Automatic Telephony by vSmith ECampbell, second edition. The selector and connector switches may besimilar to those disclosed in the patents to vKeith, Erichsoii tErickson, dlt-815,176 and #815,321, granted March 13, 1906, whenmodified to operate in a so-called tivo-wire system.

A therniionic device or vacuum tube suitable ior operation in thepresent disclosure may be similar to that disclosed in the patent toVAllcutt #1,440,432 granted January 2, 1923, in which a filamentelectrode anda plateelectrode are enclosed in an evacuated space and athird vcontrol element yiny the form oi' an electromagnetic controlwinding is placed without the evacuated space but withy its heldsurrounding the .iiist two nien.. tioned electrodes.k l

In vthis disclosure several are indicated, but it will be these symbolsmerely battery attlie exchange with .the exception of the batterieswhich are indicated within the dotted rectangles of Figs. 1, 2 and 4which are employed to control kthe ,therinioiiic device. ln the courseoit the `description, these lasty mentioned controlling batteries arereferredto as higliand low potential batteries, `but it will beunderstood that a single high y understood vthat represent one largetomatically*extended through the lineswitch.

in the well-known manner to yanidle trunk leadingto a selector switchsuch as `tha shown in Fig. l.

switch is seized, a circuit is closed `from grounded battery, throughwinding 5 ot' the control element of the therinioiiic dei/ice or vacuum'tube 6, conductor 7, left hand winding of relay 8, uppermost, backrcontact and armature of the relay 9, over conductor 10v 'of theselector trunk,., through the `line switch, over the upperv side oi thecalling line and through its substation circuits in series, yover thelower side of this line and through the line switch to conductor 1l ofthe selector trunk, right hand winding oi relay 8 to `ground. The relay8 is thus operated and at its front contact and armabatteiy symbolsvoltage battery may bofr employed. instead of these two batteries Vandof the filaments are con- As soon as the''sclecto'r except that it nowextends ture closes a circuit for actuating the slow releasingrelay 12,which relay at its lett hand armature and front contact applies a groundpotential to the holding co-nductor 13 which maintains the line switchoperated. At the right hand armature and front contact of relay 12, acircuit is closed from the low voltage battery 14 for lighting thelilament of the thermionic device 6. It should be noted that the controlelement 5 of this device acts at this time to block it so that it isinetfective. Ihe selector switch is now in condition to receive impulsescorresponding to the hundreds digit of the wanted number, and thecalling subscriber thereupon operates his dial sender to send thisseries of impulses. In response to each of these impulses, the circuitof the control element 5 of the thermionic device 6 is openedV so thatthis control element is ineffective to control the thermionic devicewith the result that an operating circuit is closed `for the primarymotor magnet 15 of the selector switch from the positive side of thehigh voltage battery 16, conductor 17, winding of the primary motormagnet, winding or' the change-over relay 18, oil-normal contacts 19,plate 2O and filament 21 oit' the thermionic device to the negative sideot' the battery 16.

The magnet 15 and the change-over relay 18 are energized in thiscircuit, but when the dial sender again closes the two sides of thecalling line, the control element 5 of the thermionic device isenergized so that magnet 15 deenergizes, but the changeover relay 18 isslow to release its arma.- tures and is thus held operated duringimpulses. In response to each impulse, the primary magnet 15 of theselector advances the brushes 22, 23 and 24: one step in their primarydirection. In response to the succeeding impulses of the hundreds seriesthe primary motor magnet 15 is energized in a circuit similar to thatpreviously described through the inner front contact and armature of thechangeover relay 18 and the cti-normal contacts 25. As soon as thechange-over relay 18 is operated, it closes an actuating circuit torrelay 26 Jfromgrounded battery, winding of this relay, uppermost vfrontcontact and armature of relay 18 to ground.

At the close ot the hundreds series ot impulses the control element 5 ofthe thermionic device is short circuited in a. circuit closed fromgrounded battery, control element 5, conductor 27, armature and backcontact ot secondary motor magnet 28, lower armature and back contact ofrelay 18, ott-normal contacts 29 to grounded battery.

The control element 5 is thus ineffective to block the thermionic device6, with the result that the secondary motor magnet 28 is energized fromthe positive side of the battery 16, winding of the secondary motormagnet 28, lower armature and front contact ot' relay 26, inner backcontact and armature ot relay 18, off-normal contacts 25, plate 2() andfilament 21 to the negative side ot battery 16. The secondary motormagnet 28 is thus energized and at its armature and back contact opensthe short circuit around control element 5, so that it is now eii'ectiveto block the thermionic device, which etfects the deenergization of thesecondary motor magnet 28. In response to each energization of the motormagnet 28 the brushes 22, 23 and 24 ot the selector switch are advancedone step in their secondary movement. The energization anddeenergization ot the secondary motor magnet 28 continues as long astest brush 2a encounters test terminals having a guarding groundpotential such as may be applied over a conductor similar to 30 fromground at the lower armature and front contact of slow releasing relay31. lVhen, however, the ungrounded test terminal 29 is reached, theswitching relay 9 is actuated from grounded battery, winding` of thisrelay, conductor 32, back contact and armature or' relay 26, conductor33, right hand armature and baci: contact ot motor magnet 28, oilnornialcontacts 3%, left hand front contact and armature ot relay 12 to ground.The switching relay 9 on actuation extends the calling line and theconductors 10 and 11 ot' the selected trunk through the selector brushes22 and 23 to the windings of relay 34; the right hand winding ot thisrelay is extended to ground, while the left hand winding of this relayis extended to grounded battery through the control element 35 of thethermionic device 36. Relay 3l is actuated in this circuit, and at itsarmatures and front contact, effects the operation o't the slowreleasing relay 31. This last named relay in turn operates to apply aguarding potential over conductor 30 and to close a circuit from the lowvoltage battery 37, through the filament 38, front contact and armatureof relay 31, side switch wiper 39 in its lirst position, uppermostarmature and back contact ot test relay 40 to the opposite side of thebattery 37. The control element 35 is etective at this time to block thethermionic device 36.

The connector switch is now in condition to receive the tens impulsesfrom the subscribers dial sender. In response to each ot theinterruptions ot the extended calling line, the control element 35 isrendered ineffective so that a circuit is closed from the positive sideot the battery 41, winding of the primary motor magnet 42, side switchwiper 43, winding oit the change-over relay dei, conductor 45, plate 46,filament 38, to the negative side of battery Litl. `When the dial senderagain closes the extended calling line the control element 35 iseil'ective to block the thermionic device 36, so that the primary motormagnet Ll2 deenergizes. ln response to each energization anddeenergization ot the primary motor magnet l2 the brushes 47, 48 and Li9of the connector switch are advanced one step in their primary movement.The succeeding impulses of the tens series are effective to energize anddeenergize the primary motor magnet l2 in the manner just described. n'the lirst energization ot' the change-over relay all, a circuit isclosed from ground, its armature and continuity spring, winding of theescape niag-y net 50, resistance 5l, to grounded battery. This circuitholds the escape magnet operated until the close of the tens series otiinpulses when the change-over relay Llill deenergizes to eiiect therelease of the escape magnet 50, which moves the side switch wipers intotheir'second position.

The connector switch is in condition to receive the units series otimpulses and the calling subscriber now operates his dial sender toeitect the last stage .in the operation ot the connector switch. lnresponse to each interruption of the extended calling line by the dialsender, the control element 235 is rendered ineffective so that anactuating circuit is closed i'or the secondary motor magnet 52 `trom thepositive side ot battery il, winding of this magnet, side switch wiperi3 in its second postion, winding ot the change-over relay ad, conductorelf, plate Li6 and filament 3S tot-he negative side ot battery 4l. Thesecondary motor magnet 52 and the change-over relay Ltil are energizedin this circuit; the change-over relay at its upper armature andcontinuity spring again causes' the energization ot the escape magnet50. lilhen the. calling line is again closed in the course ot theoperation ot' -the dial sender the control element is tire to cause thedee-nergization ot the recondary motor magnet 52, but the slow releasingchangeover relay la remains oper" ated. ln response to each cycle otenergication and deenergization of the secondary motor magnet 52, thebrushes ot the connector switch are advanced one step in their secondarymovement. At the close et the units series of impulses the controlelement blocks the thermionie device 36 Afor a relatively long intervalso that the changeover relay il deenergizes and effects thedeenergiZationot-the escape magnet 50. r his magnet thereupon moves theside switch wipers into their third. position, provided the called lineis idle. rllhe escape magnet is then actuated from grounded battery reh`sistance 5l, its winding, side switch wiper 53 to ground. Ringingcurrent is now applied to the called line from the ringing generator,winding oi the trip relay '5i-l, side switch This last named magnetthereupon vdeeuer` gizes and mores the side switch wipers into theirfourth or talking position. Guarding potential is applied to themultiple test terminals such 59 oft the called line tlufough test brushi419, side switch wiper (3() in its third and fourth positions toground. Talking battery is supplied to the calling party through thewindings'oic relay 3d, while talking battery supplied. to the calledparty through the windings ot relay 70. c c

liet is be assumed that the called line is busy at the close oli theunits series' ot` impulses, so that when-the change-over relay #istdeenergizcs, a circuit is closed from grounded batter, re; stance l,winding of the esc-ape magnet 50, continuity spring and bach Contact otrelay Ltd, winding ot the test relay hits continuity spring and backContact, side switch wi 3er 60 in its second position, test brush andthrough a multi ale test terminal such as' 59` through the test brushsuch as 49 oit the connector that has previously seized the called line,to ground through aside switch wiper such as 60 in its third or fourthposition. The escape magnet is held operated in this circuit and thetest relay l0 is operated to close a locking circuit foritselt" throughits continuity spring and innermost armature,

oituormal contacts 6l to ground. rEhe escape magnet 50 and the testrelay Ll() are thus held operateduntil the calling party` releases. Asource of busy tone B Z is then applied to the calling line through themiddle armature `and iront contact ot" the test relay l0.

rt the Vclose of the conversation when the calling subscriber replaceshis receiver on its switch hook, the relay 34 deenergizes and shortlyatterwa ds', the slow releasing relay 3l retracts its armatures. Thiscloses a cir-y cuit t'rom ground at the armature and back contact otrelay 3l oit-normal contactst,

*7 winding ot the release magnet Gi 'to 'grounded battery. The releasemagnet G4 when thus energized etlects the release ot the connectorswitch in the well known manner.

rlhe deenergization of relay 3l also remotes the holding ground from theconductor 30 so that the switching relay 9 retracts its armatiues.r Onthe restoration of ,relay 9 the release magnet 65 is energized ratusreferred to is now in condition to extend a succeeding call.

In the modiiieation of the invention shown in Figs. E3 and i theinvention is shown applied 'to a so-ealled register sender 'of the typedisclosed in my Patent No. 1,- 531,219, issued March 24, 1925. lt willbe understood, however, that this type ot register sender may be us alin any system wherein the designation ot the called line is recorded onone or more of a plurality of number storing devices located at thecentral oliice. The disclosure ot the system of Figs. 3 and f1 has beengreatly abbreviated for simplicity in description, but it will beunderstood that Fig. 4- of' this disclosure may be substituted for Fig.l of my cepending application. It such a substitution is made, relay 106(Fig. and the conductors leading thereto will be omitted.

It is believed that the present invention will best be understood bydescribing the method otl establishing a telephone connection from acalling substation such as A to a called substation such as B, referencebeing had to my mentioned patent for a complete disclosure of thedetails of the system. lVhen the subscriber at A removes his receiverfrom its switch hook primary and secondary line switches such as thoseindicated at 71 and 72 function to extend the calling line to an idlebridge circuit. rlhe extension of the calling line ettects theenergization ot the relay 73 over a circuit closed t'rom groundedbattery, lett hand winding of this relay, conductor 74e, back contactand armature of relay 75, conductors 93 and 7G of the selected bridgecircuit through the secondary and primary line switches, over the lowerside of the calling line and through the calling substation circuits inseries, over the upper side of the calling line, through the mentionedprimary and secondary line switches, conductor 7T, right hand windingot' relay Z3 to ground. The energization of relay 73 causes theoperation of the slow releasing relay 7S. The actuation of relay 78ettects the operation of relay over a circuit closed trom groundedbattery, winding of motor magnet 79, its back contact and armature,winding et the relay T5, outer back contact and armature oi relay S0,back contact and continuity spring of trip relay 81, lower back Contactand armature of relay S2, conductors 83 and S4, inner front contact andarmature et' relay 78 to ground. It need only be mentioned that thesender selector switch is normally standing with its brushes 85, 80, 88and 89 in engagement with the terminals of an idle register sender. Forthis reason the operation of relay 75 closes a circuit from ground,innner front contact and armature of this relay, selectorl brush 88,conductor 90, armature and back contact of relay 91, winding of relay 92to grounded battery. The relay 92 is operated and serves to hold theregister sender in its busy or operated condition until the releaseafter an extension oi? a call or when the calling subscriber abandons acall. The relay 92 on operation closes a locking circuit for itselfthrough its right hand front contact and armature, which locking circuitis independent et the relay 91.' Also the operation ot the relay 7.3extends the calling line through conductors 76 and 93, left handarmature' and front contact o1 relay T5, selector' brush Se', conductor94, control element 95 of the thermionic device 9G to grounded battery.The control element 95 is eilective to block the operation of the device96 at this time. Simultaneously with the operation of relay 92, thechange over relay 115 is operated in a circuit traceable from ground,inner front contact and armature of relay 75, selector brush 88, upperwinding ot relay 115, off-normal contacts 90 and 97, left hand frontcontact and armature ot relay 9S to grounded battery. The relay 92 otFig. l closes a circuit for lighting the filament 104 'from the positiveside o low voltage battery 105 to the iilament 101, conductor 106,middle front contact and armature of relay 92, conductor 10T to thenegative side of battery 105.

lt will thus be seen that the ilament is maintained lighted as long asthe register is in use and is maintained in this condition by the relay92 or by the relay 91. rl`he register sender is now in condition toreceive impulses from the calling line over the impulse circuit whichhas previously been described as including the control element 95. Theoperation ot the dial sender at the calling substation is eiiective tointerrupt this mentioned impulse circuit so that the control element 95is'ineftective to block the operation ot' the therinionic device withthe result that the motor magnet 99 is operated in a circuit traceablefrom the positive side o't battery 100, conductor 101, -winding ot'motor magnet 99, off-normal contacts 102, lower winding, front contactand armature ot' relay 115, conductor 1023, plate 10T, i'ilanient 10-1to the negative side of battery 100. The motor magnet is energized inthis circuit and since the registers are ot that type which are advancedon the energization of the motor magnet instead of on the deener- (lilgization of this magnet, the brushes of the tens register are thereforeadvanced into their second position.

It is Well understood that the in its operation intermittently opens andcloses the impulse circuit so that in response to the closure oftheimpulse circuit succeedingA the iirst mentioned interruption thereof,the control element 95 blocks the operation ot the therinionic ydevicewith t ie result that the motor magnet 99 deenergizes. 1n response tothe continued interruptions and closures ot the calling;Y line, thecontrol elementrenders the therinionic device etreetive and ineffectiveto intermittently energize` and deenergize the motor magnet 99. As aresult ot the energization and deenergization ot this motor magnet, thebrushes ot the tens register are advanced step-bystep in accordance withthe tens designation ot' the Wanted number. Atthe close ot this dialsender series et' impulses, the impulse circuit isy closed tor arelatively long` period so that the circuit including vthe lower Windingot the slow releasing relay 115 is open iior a short circuited whichrenders it inetliective tor block the operation ot the therinionicdevice ro that a circuit is closed to advance the units register troniposition 1 to position 2. This circuit is traceable troni the positiveside ol' battery 4100 conductor 101, winding of inotor magnet 108, outerlei-'t hand armature and front contact ot relay 92, loiver armature and'back Contact. ot' relay 115, conductor 108, plate 107, tllaincnt 101 tothe negative side ot' battery 100. n

lilith the units register in position 2 a circuit is closed foroperating' relay 115 traceable troni grounded battery, lett handarmature and front contacto't relay 98, units register oil-normalcontact 109, upper winding; ot relay 115, brush 88. inner right handarmature and Contact ot relay to ground. The short circuit is reruovedtroni control element 95 by the opening' otI Contact 9T when the unitsregister leaves position 1, so that the control element is againrendered effective. y

The circuits .are now in condition to rcccive the units series otimpulses. lln rcsponse to the` iirst ot' these .impulses the controlelement is rendered ineffective sothat a circuit is closed tr'oln thepositive side otl l ,.ttery 19D, conductor 101g winding el? the motormagnet 108, off normal contact 110,

lower winding, front contact and arniature ot relay 115, plate 107,tilanient 1011 to the knegative side ot battery 100. r"he motor magnet108 is thus energized kand advances the brushes of the units registerone step. lfn response to the succeeding impulses otl ia. circuittraceable from the positive sido of battery 100, conductor 101, Winding'ot this motor magnet, ortia normal contacts 110, lower Winding, trent.contact and armature oi1 change-over relay 115, conductor 108, plate10T, lilainent 10a to the negative side 'olf battery 100.

Atthe close ot. this series ot impulses, the impulse circuit is againcompleted and the control. element interrupts tor a relatively longinterval, the circuit including' the motor magnet 108 and thechange-overrelay.115. This relay thereupon deenergizes so that thisregister sender is no longer under the control ot the dial sender. Uponthe deenergization ot the relay 115, a circuit is closed tor operating'one ot' the multi-contact relays (not shown) through the units brush210, uppermost,armature and baclr contact ot relay 115, outer troutcontact and armature ot' relay 98, through both windings in series otrelay 111 to ground through the armature oit the relays similar to 111at other register' senders. 1The relay 111 is thus operated and at itsinner lett hand iront contact and armature closes circuit` for operatingthe relay 112, which circuit is completed at the innermost `lirontcontact and armature olV relay 92. Relay 112 when thus actuated, closesat its inner armature and trout contact a circuit troni ground, throughinner right hand armature, trent contact and Winding ot relay 98, tensregister brush 118 and the contacts oit the operated multi-contact relay(not shown) to the test circuit oi the called line. The conipletion otthis circuit starts the priniary and secondary line switches oli Fig'. 3to extend the called line to the terminating end ot the bridge circuit;to which 'the calling line is already conn-ected. The extension of thecalled line B to the selected bridge completes signaling* circuit t'rointhe ringing); generator, through the lett hand Winding' ot the slouYoperating trip relay 81, upper front contact and armature ol relay (nowoperated) over the upper side ot the extended circuits to the signal atthe substation B', over the lower side of the extended connection, letthand Winding ot the impedance coil 11st to ground.

Then the called party responds, the trip relay 81 is operated to openthe circuit ot' the ringing' relay and to complete a *locking* circuitfor kitself through its right hand armature and continuity s aring,lower' bach coi'itact 'and armatte ot" relay 82, nconclu'tors `8S and 1inner 'trent er neet armature the series, the motor magnet 108 isoperated oi relay T8 to ground. The operation ot the relay 81 also opensthe energizing circuit et the relay T5, whereupon this relay decnergizesand at its inner front contact and armature, the circuit ot relay 92 isopened :ausing it to retract its armatures. rIbis last mentionedoperation results in the restoration ot the tens and units registers totheir normal positions. The deenergization ot' relay T5 has opened thecircuit et the control element 05 so that the release et relay 02 closesa circuit from the positive side ot the battery 100, winding ot magnet108, off normal contacts 110, outer back contact and armature ot' relay92, lower back contact and armature of relay 115, plate 10i andVtilament 104. liiagnet 108 is energized in this circuit and advances tieunits register one step towards its normal position, however, theenergization ot the motor magnet 108 also closes a circuit forenergizing the control element 95, which circuit is traceable 'fromgrounded battery, winding of the control element, conductor 116, 'rontcontact and armature of magnet 108, inner Jfront contact and armature ofrelay 91, resistance to ground. rihe completion et this circuit iseti'ective to block the operation ot the thermionio device so that themotor magnet 108 deenergizes and opens the circuit of the controlelement, thereupon the operating circuit of the motor magnet 108 isagain completed to advance the brushes ot the units register anadditional step toward their normal position. The energization ot magnet108 a1so closes again the circuit for the control element. rthis cycleof operations is repeated until the units register reaches its normalposition at which time the cti normal contacts 110 are opened and theott-normal contacts 10?J are closed. rEhe motor magnet S9 of the tensregister is now energized in a circuit traceable from the positive sideof the battery 100, conductor 101, winding ot' the motor magnet 9S),ott-normal contacts 102, back contact and armature of relay 99., bac-ltcontact and armature ot relay 115, plate 107, lilaiuent 10i4 to thenegative side ot battery. The motor magnet is energized in this circuitand advances the brushes ot the tens register one step towards theirnormal position. The energization ot the motor magnet 90 also closes anenergizing' circuit tor the control element 0:. in a manner similar tothat aire: dy described. rl`he cycle of operations described 'tor theunits register is now repeated in the tens register to cause theoperation ot' the motor magnet 09, until the tens register reaches itsnormal position at` which time the ott-normal. contacts 118 are openedto permit the release ot relay 91 and the consequent interruption of thecircuit of filament 1011.

Vhile the operation of this register sender has been described inconnection with an au- Lacasse tomatie telepl'ione system such as that'disclosed in my mentioned patent, it will be understood that thisinvention is suitable for any telephone system wherein registers urecont-rolled from a remote point to store the designation ot a wantedtelephone line and thereafter control the setting ot automatic switchesto extend a calling line to a call rd line. The present invention isalso particularly adapted for use in a telephone syst cui such as thatdisclosed in the patent to Lundell #1,108,819 granted January 18` 1910.

llirhat- I consider to be novel in the system ot Figures and t is theuse ot' a remotely controlled thermionie device to variably set a seriesof number storing devices in succession and thereafter cause theseregisters to control the setting of one or more automatic switches toextend a calling line to a called line.

That is claimed is 1. ln an automatic telephone system, an incomingcircuit, outgoing circuits, automatic switching means for extending saidincoming circuit to any ot said outgoing circuits, a source of directcurrent, and means4 including an electron discharge device provided witha control element, an impulse circuit including said control elementextending over two sides ot said incoming circuit in series, saidcontrol element being governed over said impulse circuit by curr-entfrom said source for directively controlling said automatici switchingmeans.

2. In an automatic telephone system, an incoming circuit, a pluralityot' outgoing circuits, a progressively movable automatic switch forinterconnecting said incoming` circuit with any ot said outgoingcircuits, a source of direct current, and means including a thermioniedevice provided with a control element, an impulse circuit includingsaid control element extending over the two sides ot said incoming linein series, said control elcment being governed over said impulse circuitby current trom said source Ylor direc-tively controlling the operationoit said automatic switch.

53. ln an automatic telephone system, an incoming circuit, a pluralityo'l outgoi y.- circuits, an autoi'natic step-by-step switch 'torintcrconnecting said incoming circuit with any ot said outgoingcircuits, a source o direct current, and means including a thermionicdevice provided with a control clement, an impulse circuit including.said control clement extending over the t-wo sides ol said incomingline in series, said control element being governed over said impulsecircuit by current trom said source for directively governingtheoperation ot' said automatic switch.

1. In an automatic telephone system, an incoming circuit, a plurality ofoutgoing eircuits, automatic switching means for interlll connectingsaidincoming cir-cuit with any of said outgoing circuits, amotor magnet forcontrolling the operation ot said automatic switch, a surce of directcurrent, a multielectrode thermionic device directively controlled bycurrent from said source over said incoming circuit, and a circuit forsaid motor magnet including electrodes otfsaid thermionic device.

5. In an automatic telephone system, an incoming circuit, a plurality ofoutgoing;` circuits, an automaticswitch for extending said incoming,lcircuit to a wanted outgoing` circuit, a motor magnet for advancingsaidauto-y matic switch, a thermio'nic device having a plurality ofelectrodes enclosed within an evacuated space, a third control electrodeior said tl'iermionic device, said third electrode being remotely anddirectively controlled `from a distant point, and a circuit of saidmotor magnet extending,` across the space be outgoing circuits, aplurality oi" motor mag;y

nets operating` in` succession, operating circuits for said motormagnets, a thermionic device having a plurality of electr des within anevacuated space, a control element for said thermionic device arrangedto be .directively controlled from a remote point, and a relay forclosing the circuits of said motor magnets in succession, the 'operatingcircuit for one 'of said motor magnets serially inclu'dingg,` thewinding` of said relay and the space between said electrodes.

7.,]n an automatic telephone system, au incoming` circuit, a pluralityof out3,oing;l circuits, automatic switching' means for ex tending saidiucomingcircuit to any oil said outgong crcuits, a source oi' directcurrent, a thermion'ic device having two .elements enclosed' within anevacuated space, means for causing a space current between saidelectrodes, an additional element `itor said thermionic device` animpulse circuit in Which said element is connected including' two sidesin series oi saidjincoming; circuit.v said element being,` remotelycontrolled from said source of current, over said impulse circuit tovary said space current, and means including said space current forcontrolling;

the operation of said automatic switching` means.

8. In an automatic telephone system, an incoming* circuit, a pluralityof outgoing circuits, means including; switches and a link circuit forextending said incoming' circuit to a wanted outgoing circuit, athermionic device having a ilament, a plate and a control electrode fordirec-tively controlling thc operation of one of said automaticswitches,

and means controlled by the seizure of said link circuit forautomatically lighting said filament. i

9. ln anautomatic telephone system, au incoming circuit, a plurality ofoutgoing;` circuits, means including` switches and a link circuitforextending saidincoining circuit to a Wanted outgoing circuit, atherniionic device having a iilament'Y a plate and a control electrodefor directively controlling` the operation of one of said automaticswitches, means controlled by the seizure ot said link circuit forautomatically lighting` said ila ment, and means for extinguishing` saidiilament when the link circuit has been extended to the wantedoutgoing,` circuit.

l0. ln an automatic telephone system, an incoming circuit, aplurality otoutooirip` circuits, automatic switching` means `tor extending saidincoming circuit to a wanted outgoing' circuit, a plurality of motormagnets` for said automatic switching means, a source ot' directcurrent, a thermionicdevice havingan input circuit including said sourceand the two sides of said incoming circuit in series for directivelyrcontrolling.,y in succession said motor magnets.

- ll. ln an automatic telephone system, an incomin` circuit, a pluralityoi: outgoing circuits, a plurality of link circuits, each provided withan automat-ic switch, a thermionic device at each link circuit forgoverning the operation of its automatic switch7 means in.- cluding aseries ofr said link circuits and automatic switches for progressivelyextending said incoming circuit to a wanted out going` circuit, andmeans at a remote point for controlling' the thermionic device of aselected link circuit and for disabling the thermionic device oit the.preceeding link circuit in the series.

l2. lnan automatic telephone system, an incoming,` circuit, a pluralityof outgoing;

circuits, two groups ot link circuits, each o' i said link circuitsbeing;` provided with an automatic switch, thermionic devices associatedwith certain of said linkcircuits ot each `uroup for controlling saidautomatic switches, means controlledover the two sides in series oi saidincoming"circuit to actuate a thermionic device whereby a link circuitand its switch in each `group cooperate to extend said incoming' circuitin a connection to a wanted outgoing;- circuit, and 'means controllcdover said connection from the last link circuit thcreotl 'tor releasingsaidy connection. n

13. ln an automat-ic telephone system, a telephone line, a plurality ofoutgoing` circuits, a connecting circuit provided with automatic meansfor extending` said connectingcircuit to a wanted outgoing circuit overa metallic connection, a thermionic device remotely controlled over twosides of said telephone line in series for directively governing saidconnection, and means including a nonnumerical switch ior extending saidtelephone line to said connecting circuit.

1st. In an automatic telephone system, a series of automatic switcheseach provided with a thermionic device for governing the same, a controlcircuit common to said thermionic devices, and'means for transferringsaid control circuit to said thermionic devices in succession.

15. In an automatic telephone system, a calling telephone line, aplurality of other telephone lines each provided with terminals, asource of direct current, automatic switching means including atherlnionic device directively controlled over the two sides of saidcalling telephone line in series from said source for causing saidswitching means to connect said calling telephone line over a metallicconnection to terminals ot a wanted telephone line, and means etectiesubsequent to the operation oic said thermionic device for signalingsaid called telephone line.

16. In a telephone system, an incoming line, a plurality of outgoinglines, an automatic switch for interconnecting said incoming line withany of said outgoing lines, a source of direct current and an impulsesender associated with said incoming line, an electron discharge deviceprovided with an input circuit and an output circuit, means includingsaid source of current and said impulse sender for transmittin'gimpulses of direct current to said input circuit, and means in theoutput circuit controlled by current impulses in said input circuit fordirectively operating said automatic switch.

` 17. In a telephone system, an incoming` circuit, a plurality ofoutgoing circuits, an automatic switch for interconnecting said incomingcircuit with any of said outgoing circuits, an impulse sender associatedwith said incoming circuit, an electron discharge device includingtwoelectrodes enclosed within an evacuated space, a control electrodeexternal to said evacuated space, an output circuit including said firstmentioned electrodes, means including said incoming circuit'and saidcontrol electrode for producing energy variations in said outputcircuit, and means responsive to said energy variations for directivclyop .rating said automatic switch to extend said incon'iing circuit to anoutgoing circuit.

1S. In a telephone system, an incoming circuit, a plurality of outgoingcircuits, an automatic switch for extending said incom- Lacasse trollingthe electrical condition between said electrodes, means including saidincoming circuit and said coil in series for producing energy variationsin said output circuit, and means responsive to said energy variationsfor directively operating said automaticswitch.

19. In a telephone system, a telephone line, a plurality of linkcircuits each provided with an automatic switch, said link circuits andautomatic switches being arranged for connection in tandem to extendsaid telephone line to any outgoing line, an electron discharge deviceassociated with each link circuit, each electron discharge device beingprovided with two electrodes included within an evacuated space and acoil surrounding said evacuated space to control the electricalcondition between said electrodes, means including said telephone lineand the electron discharge device of one of said link circuits forextending said telephone line and said link circuit to a second linkcircuit, and means including a part of said iirst mentioned means andthe electron discharge device ot said last mentioned link circuit forcausing the automatic switch of said last mentioned link circuit toextend this last mentioned link circuit to an outgoing telcphone line, v

Q0. In a tel phone system, an incoming circuit, a plurality of outgoingcircuits, an automatic switch for extending said incominO' circuit toany outgoing circuit, an electron discharge device for controlling saidautomatic switch, said electron discharge device being provided with apair of electrodes and a controlling electrode, an output circuitincluding said pair of electrodes, an impulse circuit including saidcontrol electrode in series with a control relay and said incoming line,means for generating directive impulses in said impulse circuit forcausing energy variations in said output circuit, means responsive tosaid energy variations for dircctively operating said switch, areleasing mechanism or said switch, and a slow releasing relaycontrolled bysaid control relay for governing the release of saidautomatic switch.

In witness whereof, I hereunto subscribe my name this 2nd day ot' March,A. D., 1923.

VINFRED T. POWELL.

